Enrichener.. not likely.. but as likely as the plugs. I think if more detail had been offered perhaps a more specific answer could have been issued. I do agree that jetting is a suspect, but if i had a doller for every evo rider ive met complaining about the bike buck on hard acceleration id be rich.. with an evo even running aftermarket carbs you must Roll the throttle.. you can crack it.. that not how the evos powerband works. Roll it and enjot the full puch of your ride..now thats the simple fix. Clean your carb and jets. I just pull it off wipe the bowl out and remove the jets and poke a single strand of wire from a bicycle cable through it. REPLACE the needle and seat 9 times out of 10 if tje bowl sticks open youl flood out at high speeds but if thats the case youl also see your overflow under the bike %!¤ing gas on the ground. Make sure your petcock is flowing strong and while on the tank make sure you venting.. vapor lock will starve the bike on hard acceleration as it only allows a small flow due to vacume restriction.